Control apparatus for fuel injection system

ABSTRACT

A control apparatus for an internal combustion engine fuel injection system has a cam rotatable between a normal position and a cold-starting position, a cam follower movable in response to engine intake manifold pressure to vary the position of a metering valve control stop in accordance with said pressure and with the cam position, and a latch pivotally mounted on the cam and biased so as to limit movement of said control stop, and hence fuel flow, when the engine is started with the cam in its normal position. The latch is moved by the cam follower to an inoperative position when the engine is running. A damping arrangement slows movement of the latch in response to its biasing means.

Umted States Patent 1 [.111 3,776,210

Beasley et al. Dec. 4, 1973 CONTROL APPARATUS FOR FUEL [56] References Cited INJECTION SYSTEM UNITED STATES PATENTS [75] Inventors: Gordon Frank Beasley, Birmingham; 2,965,091 12/1960 Munyan 123/139 AM George Whitehurst, Solihull, wfll'wickshil'e, both of England Primary ExaminerLaurence M. Goodridge [73] Assignee: Joseph Lucas (Industries) Limited, Att0mey ]hn Holman et Birmingham, England 57 ABSTRACT [22] Filed: Feb. 4, 1972 I l A control apparatus for an internal combustion engine [21] Appl. No.2 223,438 fuel injection system has a cam rotatablebetween a normal position and a cold-starting position, a cam [30] Foreign Application Priority Data follower movable in response to engine intal e manifold pressure to vary the position of a metering valve Great 5857/ 71 control stop in accordance with said pressure and with May 2, 1971 Great Bntam 4,094/71 the cam position, and a latch pivotally mounted on the cam and biased so as to limit movement of said con- [52] 5 trol stop, and hence fuel flow, when the engine is started with the cam in its normal position. The latch is moved by the cam follower to an inoperative posig tion when the engine is running, A damping arrange- 1 g ment slows movement of the latch in response to its 140 M 179 biasing means.

6 Claims, 2 Drawing Figures 3,776,210 WET 2 r? PATENTED DEC 4 I975 CONTROL APPARATUS FOR FUEL INJECTION SYSTEM This invention relates to a control apparatus for an internal combustion engine fuel injection system of the type which includes a shuttle metering device wherein the amount of fuel injected is variable by means of a control stop. It is an object of the invention to provide such an apparatus in a convenient form.

According to the invention a control apparatus for a fuel injection system of the foregoing type comprises an edge cam pivotal about an axis in response to a control which is operable during cold starting of an associated engine, a cam follower movable relativeto the cam in response to the pressure in an intake manifold of the engine, a plunger engageable at one end thereof with the cam follower and coacting with said control stop,

- latch means pivotally mounted on said cam and engageable with said one end of the plunger to restrict fuel supply to the engine, and abutment means engageablewith the latch means to move the latter away from the plunger when said cam is moved in response to said control, means biasing said latch means towards said engagement with the plunger and damping means opposing movement'of said latch means by said biasing means.

Examples of control apparatus according to the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a section through an apparatus, and

FIG. 2 is a section through an alternative form of apparatus.

Referring to FIG. 1, a shuttle-type metering device, shown generally at 10. includes a control stop 11 which controls, in a known manner, the amount of fuel injected into an associated engine, fuel is supplied to the device by a pump 12. The control apparatus has a casing 13 within which an edge cam 14 is secured to a pivotally mounted spindle 15. Cam 14 is biased in a clockwise direction, as shown in the drawing, by a spring 16. Cam 14 is rotatable against the bias of spring 16 by an external engine throttle control, applied via spindle 15. Clockwise movement of cam 14 is limited by a stop .17.

A cam follower 18 includes a pair of arms 19 between which are mounted rollers 20 which engage cam 14. Follower 19 is movable in the plane of cam 14 by a diaphragm arrangement 21 responsive to the depression in the intake manifold of the engine. A plunger 22 has a face engageable with rollers 20 and abuts the control stop 11. Plunger 22 is biased by a spring 33 away from rollers 20.

A latch 23 is mounted on cam 14 for movement about a pivot 24 and is engageable with face 25 of plunger 22, a torsion spring 26 biasing plunger 22 towards such engagement. Latch 23 lies between arms 19 and includes an arm 23a lying between arms 19 of follower 18. Arm 23a is engageable by a pin 27 which extends between the arms 19. An adjustable stop 28 engages a projection 29 on latch 23 and comprises a threaded stud in which a plunger 31 is a sliding fit.

{Plunger 31 is biased into engagement with portion 29 by a light compression spring 32.

In use. during cold starting cam follower 18 is at the extreme left hand end of its travel, there being no depression in the engine intake manifold. Cam 14 is moved anticlockwise by the external control, which is operated only during cold starting. Engagement of projection 29 first against plunger 31 and then against stud 30 causes latch 23 to be moved clockwise away from face 25. Downward movement of plunger 31 is initially resisted by air trapped behind plunger 31 which thus provides a dashpot arrangement. Control stop 11 and plunger 22 can thus be displaced downwardly against spring 33 by pressure delivered by pump 12, until plunger 22 engages rollers 20. A maximum amount of fuel is thereby delivered to the engine. When the engine starts, an increase inmanifold depression moves follower 18 to the right along cam 14 displacing plunger 22 and control stop 11 upwards to reduce fuel flow. With cam 14 returned to its normal operating position, fuel flow continues to be controlled by manifold depression, latch 23 resting on the side of plunger 22.

When the engine is stopped and no fuel is being delivered by pump 12, control stop 11 and plunger 22 are displaced upwards to their full extend by spring 23. Latch is then moved by spring 26 to the position shown in the drawing, in which position latch 23 engages face 25 of plunger 22. During hot starting of the engine cam 14 remains in its fully clockwise position. Latch 23 is thus not displaced, and by engagement with face 25 limits the amount of fuel supplied to the engine.

If the engine is over-running the resultant high manifold depression moves cam follower 18 to the right to reduce fuel flow to the engine. Pin 27 displaces latch 23 out of the path of plunger 22 as previously described. During subsequent acceleration, follower 18 moves to the left to increase fuel flow, and latch 23 is urged anticlockwise by spring 26. Plunger 31, which is urged into engagement with projection 29 acts as a dashpot, as previously described, to damp movement of latch 23 in response to spring 26.

The delay imposed on latch 23 enables plunger 22 to move downwards after follower 18 before latch 23 moves into the path of plunger 22. Latch rests against the side of plunger 22 as before.

The apparatus thus permits over-fuelling during cold starting, but prevents this during hot starting.

The alternative form of apparatus shown in FIG. 2 is generally similar to that of FIG. 1, corresponding components being assigned corresponding reference numbers. The adjustable stop 28 is in this case, however, in the form of a plain stud. A helical spring 30 has one end rigidly secured to a further projection 34 on latch 23. Secured to the other end of spring 30 is a resilient, part spherical, hollow rubber part 35 which lies adjacent a wall casing c sing 13. A passage 38 extends through the casing wall adjacent part 35. Passage 38 communicates via restrictor 34 with the engine intake manifold.

Operation of the apparatus of FIG. 2 is substantially the same as that of the apparatus of FIG. 1, except that when the engine is over-running, the resultant high manifold depression moves cam follower 18 to the right to reduce fuel flow to the engine, pin 27 ensuring that latch 23 is dipslaced out of the path of plunger 22 as previously described, rubber part 35 being brought into contact with the adjacent part of casing 13. The manifold depression is transmitted via passage 38 to flatten part 35 against the adjacent part of the casing 13, so that, through the medium of spring 30, latch 23 is held in its clockwise position. During subsequent acceleration, follower 18 moves to the left, and latch 23 moves anticlockwise under the influence of spring 26 at a rate dependent on the rate of increase in pressure in passage 38. The rate at which pressure in passage 38 increases depends on the size of restrictor 36 and its distance from part 35. Movement of latch 23 to follow cam follower 18 is thus damped to an extent depending on the size and location of restrictor 36.

The delay enables plunger 22 to move downwards after follower 18 before latch 23 moves into the path of plunger 22. Latch 23 rests against the side of plunger 22 as before.

We claim:

1. A control apparatus for an internal combustion engine fuel injection system which includes a shuttle metering device whereby the amount of fuel injected is variable by a control stop, comprises an edge cam pivotal about an axis, in response to a control which is operable during cold starting of an associated engine, a cam follower movable relative to the cam in response to the pressure in an intake manifold of the engine, a plunger engageable at one end thereof with the cam follower and coacting with said control stop, latch means pivotally mounting on said cam and engageable with said one end of the plunger to restrict fuel supply to the engine, and abutment means engageable with the latch means to move the latter away from the plunger when said cam is moved in response to said control means biasing said latch means towards said engagement with the plunger and damping means opposing movement of said latch means by said biasing means.

2. An apparatus as claimed in claim 1 which includes an abutment on said cam follower and engageable with said latch means to move the latter away from engagement with the plunger as the cam follower moves in response to a fall in intake manifold pressure.

3. An apparatus as claimed in claim 1 in which the means biasing the latch means towards engagement with the plunger comprises a torsion spring.

4. An apparatus as claimed in claim 1 in which said abutment means comprises a stud whose position relative to the pivotal axis of said cam is adjustable.

5. An apparatus as claimed in claim 4 in which said damping means comprises a further plunger slidable within said stud and a spring urging said further plunger into engagement with said latch means.

6. An apparatus as claimed in claim 1 in which said damping means comprises a hollow, resiliently deformable abutment, a passage connecting the inside of said element with said engine intake manifold and a spring means connected to said deformable element and to the latching means, whereby a suction in said intake manifold pressure causes said spring means to apply an increased force to said latch means. 

1. A control apparatus for an internal combustion engine fuel injection system which includes a shuttle metering device whereby the amount of fuel injected is variable by a control stop, comprises an edge cam pivotal about an axis, in response to a control which is operable during cold starting of an associated engine, a cam follower movable relative to the cam in response to the pressure in an intake manifold of the engine, a plunger engageable at one end thereof with the cam follower and coacting with said control stop, latch means pivotally mounting on said cam and engageable with said one end of the plunger to restrict fuel supply to the engine, and abutment means engageable with the latch means to move the latter away from the plunger when said cam is moved in response to said control means biasing said latch means towards said engagement with the plunger and damping means opposing movement of said latch means by said biasing means.
 2. An apparatus as claimed in claim 1 which includes an abutment on said cam follower and engageable with said latch means to move the latter away from engagement with the plunger as the cam follower moves in response to a fall in intake manifold pressure.
 3. An apparatus as claimed in claim 1 in which the means biasing the latch means towards engagement with the plunger comprises a torsion spring.
 4. An apparatus as claimed in claim 1 in which said abutment means comprises a stud whose position relative to the pivotal axis of said cam is adjustable.
 5. An apparatus as claimed in claim 4 in which said damping means comprises a further plunger slidable within said stud and a spring urging said further plunger into engagement with said latch means.
 6. An apparatus as claimed in claim 1 in which said damping means comprises a hollow, resiliently deformable abutment, a passage connecting the inside of said element with said engine intake manifold and a spring means connected to said deformable element and to the latching means, whereby a suction in said intake manifold pressure causes said spring means to apply an increased force to said latch means. 